Pressure chuck



G. E. BONIN PRESSURE CHUCK July 22, 1969 2 Sheets-Sheet 1 Filed Nov. 16, 1966 Fig. 7

PRIOR ART PRIOR ART INVENTOR. GEORGE E. BONIN By 1 4 )fm ATTQRNEY G. E. BONIN PRESSURE CHUCK July 22, 1969 2 Sheets-Sheet 2 Filed Nov. 16, 1966 Fig. 4

| I JNVENTOR.

GEORGE E. BONIN BY J14 ATTORNEY United States Patent 3,456,399 PRESSURE CHUCK George E. Bonin. Addison, N.Y., assignor to Corning Glass Works, Corning, N.Y., a corporation of New York Filed Nov. 16, 1966, Ser. No. 594,938 Int. Cl. B24b /00, 41/06, 19/00 US. Cl. 51-237 6 Claims ABSTRACT OF THE DISCLOSURE I With the advent of new cooking surface materials which transfer heat from an input source, such as gas or electricity, to the bottom of culinary ware items positioned thereon, it has been found that maximum heat transfer is obtained when the bottom surface of the culinary item is in virtual continuous contact along its extent with the cooking surface. Accordingly various techniques of accurately finishing the bottom surface of culinary items have been investigated in order to obtain optimum finishing characteristics with acceptable dimensional tolerances.

In the past it has been customary to utilize a pitch or wax blocking operation in performing precision work, such as is now necessary in order to obtain maximum thermal efficiency from the culinary items. The blocking method, however, has not been completely satisfactory since it requires the setting or pitching of a block in each piece of ware which is proceeding through the finishing process of grinding, fine lapping and polishing. Not only does this require a large inventory of pitching blocks, but also necessitates a time consuming operation in positioning and pitching the block in each ware item for transfer along the finishing operation.

Vacuum chucking of ware items has also been proposed in the past. However, it has been found that the vacuum deforms the ware during the finishing operation, and although a uniform surface is provided during such operation, an irregular surface results When the vacuum is released. Accordingly, vacuum chucking has not proved to be completely satisfactory for the intended purpose.

Briefly, my improved structure for chucking ware items incorporates a plurality of back-up segments which are flexibly suspended from three points on a pressure-connector plate. Preferably, the plurality of back-up segments are symmetrical or indentical with each other, in that they are suspendably connected at their centers of gravity so as to provide a built-in equality with regard to uniform pressure distribution and flexibility. A resilient material overlies the face of the plurality of back-up segments so as to uniformly distribute the pressure exerted by such segments over the backing or inner surface of the ware item to be finished.

It thus has been an object of the present invention to provide an improved ware holder chuck for precision finishing work, which eliminates the disadvantages-accompanying the known pitching block and vacuum chuck holders.

A further object of the invention has been to providean improved ware holder chuck construction for precision finishing operations which easily engages and disengages a workpiece, so that only one chuck is required per operating spindle, instead of one chuck per ware article as required in the pitching block operation.

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An additional object of the invention has been to provide an improved ware-holding chuck construct-ion having :a plurality of flexibly suspended back-up sections which exert uniform pressure across the back of the surface to be finished, so as to facilitate the obtainment of improved dimensional tolerances.

These and other objects of my invention will become apparent to those skilled in the art from the following disclosure and accompanying drawings in which:

FIG. 1 is a top plan view of a typical pitching block arrangement previously utilized to obtain precision work;

FIG. 2 is a cross-sectional view in elevation taken along IIII of FIG. 1;

FIG. 3 is a top plan view of an improved ware-holding chuck embodying the present invention; and

FIG. 4 is a cross-sectional view in elevation taken along line IVIV of FIG. 3.

Referring now to FIGS. 1 and 2, a ware item 10, having a bottom surface to be finished 11, is shown having a pitching block 13 positioned therein. The pitching block is provided with a plurality of spacing or contact feet 14 which restupon the inner bottom surface 12 of the ware item 10. The pitching block 13 is provided with a central spindle-connecting portion 15 and a plurality. of hollow position-retaining portions 16. The block 13- is carefully positioned and centered within the ware article 10 and then molten pitch or wax 17 is poured between the block and the inner surface of the ware item, and flows upwardly Within the hollow position-retaining portions 16 to firmly position the block 13 within the article 10 when the pitch or wax 17 hardens.

It thus can be seen that the conventional pitch or wax blocking operation requires an extensive inventory of pitching blocks, since each ware item along the finishing process, including grinding, lapping, and polishing, must be supplied with its own or individual pitching block. Further, the utilization of a pitching block necessarily requires a considerable amount of time in view of the fact that the block must be evenly centered Within the ware item and retained in such position until the pitch hardens. Then too, there is the problem of removing the pitching block and hardened pitch from the Ware item after the finishing operation is completed.

Referring now to FIGS. 3 and 4, an improved easilyappliable ware-holding chuck 20 is shown positioned within Ware item 10. The chuck 20 is connected to a downfeed spindle shaft 21 through a universal joint 22, affixed to a triangular connecting-pressure plate 23. A plurality of substantially identical or symmetrical back-up segments 24, 25, 26, 27 are flexibly secured to pressure-connecting plate 23 in such a manner so that a downward force exerted on such plate will be distributed uniformly to the various back-up segments.

As shown, segments'26 and 27 are connected to plate 23 by means of a connecting bar 28. The bar 28 is flexibly secured to plate 23 by means of a bolt 29 having adjust able lock nuts 30. Preferably, the lock nuts 30 are so positioned on bolt 29 so as to allow limited flexing movement between the plate 23 and connecting bar 28, Although the exact configuration of plate 23 is not critical, it can be appreciated that the triangular nose P rtion, through which bolt 29 passes, in effect facilitates relative movement of bar 28 with respect to the plate 23. The segments 26 and 27 are in turn flexibly connected to bar 28 by means of bolts 31 and adjustable lock nuts 32, similar to bolt 29 and nuts 30. By adjusting the position of lock nuts 32 on each bolt 31, it is possible to provide for limited flexing movement between the segments 26, 27 and the connecting bar 28.

Back-up segments 24 and 25 are also connected to plate 23 by means of bolts 31 having adjustable lock nuts 32. However, in order to position segments 24 and 25 in the same .plane as segments 26 or segment 24 and 25 is provided with a spacer member 33, intermediate the connecting plate and the individual segment. The spacers 33'cooperate with the adjustable lock nuts 32 on bolts 31 to permit limited flexible movement of back-up segments 24 and 25 with respect to connecting plate 23. Y

It thus can be seen that the various back-up segments are, in effect, connected to plate 23 by means of a threepoint suspension which provides for stability and uniformity in the application of pressure to the work article. Further, each backup segment is preferably connectably and 27, each connecting bolt suspended at its center of gravity by bolt 31 so as to further facilitate the uniform distribution of pressure about the entire face of the ware-holding chuck. Finally, the back-up segments are provided with a continuous resilient facing material, such as a rubber pad 34, in order to further evenly distribute pressure to the inner surface of the ware article. If desired the pad 34 may be notched, slit, or scored intermediate the various back-up segments to provide additional flexibility and resiliency.

In operation, a ware article 10, having a surface 11 to be finished, is positioned upon a rotatable finishing wheel 35 such as a lap or mill, and the ware-holding chuck is brought into cooperative engagement with the inner surface of the ware article. Spindle shaft 21 functions as a down-feed and exerts its force through universal joint 22 to pressure-connecting plate 23. The shaft 21 may be positively 'rotated or idled, as desired, during its downfeeding operation. The universal joint 22 not only permits the application of uniform pressure to plate 23 irrespective of the position of spindle 21, but also insures against uneven pressures being generated in the ware article through a cocked or skewed holding chuck. In addition, the flexible connection to each back-up segment compensates for any irregularities in the inner surface of the ware item, whereas the three-point suspension from plate 23 insures a stable uniform distribution of pressure from such plate to the various segments. The pressure exerted by the segments is transferred uniformly through the rubber pad 34 to the inner surface 12, so as to insure that the outer surface 11 to be finished is in constant uniform contact with the finishing wheel 35.

Although four wooden segments have been shown in the drawings, it is to be understood that the invention is not intended to be limited by either the material or particular configuration shown. That is, other combinations of back-up segments of virtually any suitable material may be utilized, as long as they are substantially identical or symmetrical with each other in order to dis s'eminate a uniform distribution of pressure across the entire face of the segments. I have found that my improved Ware-holding chuck provides a flatness having tolerances of .002 inch over 8 inches of surface, and at a rate not heretofore obtainable with the pitch blocking operation. In addition, an even load is distributed over the eritire surface of the ware article; however, due to the built-in flexibility which is provided by the various segmerits, allowance is made for slight flexing of uneven surfaces, and accordingly'it is possible to finish such articles within allowable tolerances. Although the Wareholding chuck of the present invention is shown operatively holding a glass culinary ware item, the invention has equal applicability for finishing ware items of metal, glass, refractory, or semi-crystalline materials. v I Although I havedisclosed the now preferred embodiment of my invention it will be apparent to those skilled in theart that various changes and modifications may be made thereto Without departing from the spirit and scope thereof as defined in the following claims. I claim:

I. An improved flexible an even load over pressure chuck for applying the entire surface to be finished of a i ware article'while'flexibly compensating for uneven surfaces so as to produce ware having improved flatness tolerances wherein the improvement comprises, a plurality of spaced-apart pressure segments formed to substantially completely overlie theback of the surface to be finished, a resilient member overlying surface portions of said plurality of pressure segments to facilitate an even distribution of applied load from said segments to the back of the surface to be finished, a rotatable down-feed member, a connecting plate pivotally connected to said downfeed member, and adjustable connecting means independently flexibly securing said plurality of pressure segments to said connecting plate.

2. An improved flexible pressure chuck as defined in claim 1 wherein said adjustable connecting means includes means for flexibly engaging each of said pressure segments at its center of gravity, and a three-point suspension sys tem for connecting said pressure segments to said connecting plate.

3. An improved flexible pressure chuck as defined in claim 1 wherein said connecting plate has a substantially triangular configuration, a spacer bar flexibly connected to said connecting plate adjacent one corner thereof, a pressure segment flexibly'connected to one end of said spacer bar, a second pressure segment flexibly connected to the opposite end of said spacer bar, a third pressure segment flexibly connected to said connecting plate adjacent a second corner thereof, and a fourth pressure segment flexibly connected to said connecting plate adjacent a third corner thereof.

4. An improved flexible pressure chuck as defined in claim 1 wherein threaded mounting means adjusts the degree of flexibility of the mounting of each of said pressure segments.

5. An improved flexible pressure chuck for precision finishing ware articles wherein the improvement comprises, a pressure plate, a plurality of substantially identi cal individual spaced-apart back-up segments, means flexibly suspending said individual back-up segments from said pressure plate, resilient means overlying surface portions of said back-up segments, and said suspension means including a three-point flexible suspension from said pressure plate.

6. An improved flexible pressure chuck for precision finishing ware articles wherein the improvement comprises, a pressure plate, a plurality of substantially identical individual spaced-apart back-up segments, means flexibly suspending said individual back-up segments from said pressure plate, resilient means overlying surface portions of said back-up segments, adjustable connecting means flexibly connecting'a plurality of said back-up segments directly to said pressure plate, bar means flexibly connected to said pressure plate, and a plurality of back-up segments flexibly connected to said bar means.

References Cited v UNITED STATES PATENTS 791,027

MY=RON c. KRUSE, Primary Examiner U-S-CI-X-R- 51 -227", i 

